Controls for gas-burning systems

ABSTRACT

1,108,251. Valves. SERVOTOMIC Ltd. 5 Jan., 1966 [13 Jan., 1965], No. 1471/65. Heading F2V. [Also in Division F4] In a gas burning system (see Division F4) a temperature controlled valve comprises gas inlet 30 and outlet 31 and a valve member 32 biased by a spring 35 which urges it into a position to cut off the gas. A rod 36 secured to the member 32 rests via a rod 39 on an &#34; Invar &#34; (Registered Trade Mark) rod 40 received in a brass tube 41 surrounded by a container 29. As the valve becomes heated; e.g. by water of a central heating system passing through container 29, the brass tube expands more than rod 40 causing member 32 to cut off the gas. A second valve is described which forms the subject of Specification 1,108,251.

March 26, 1968 Filed Jan. 11, 1966 F. CARR CONTROLS FOR GAS-BURNINGSYSTEMS 3 Sheets-Sheet 1 QO FQI 78 89 23 Q4 March 26, 1968 F. CARRCONTROLS FOR GAS-BURNING SYSTEMS 5 Sheets-Sheet 2 Filed Jan. 11, 1966 II I I I I I I I lll.lfllJ)/li March 26, 1968 F. CARR 3,374,952

I CONTROLS FOR GAS-BURNING SYSTEMS Fil'ed Jan. 11, 1966 5 Sheets-Sheet 5United States Patent ABSTRACT OF THE DISCLOSURE The specificationdiscloses a gas-burning system having a main burner, a pilot burner andan auxiliary burner. Operation of the auxiliary burner controls the gassupply to the main burner. The system includes a main-burner, gas-supplyvalve which acts both as a shut-off valve for the main burner and, whenit is open, as a pressure governor for the gas supplied to the mainburner. This valve is controlled in dependence on operation of theauxiliary burner. In one embodiment, the auxiliary burner can also besupplied from a gas control valve which operates as a shut-off valve andalso as a pressure governor when open. In a second embodiment, thesupply valve for the main burner is controlled in dependence on theoperation both of the pilot burner and of the auxiliary burner.

In present gas-burning systems there are at least three sensing elementseach of which may control a separate valve in the gas supply independence on the conditions sensed. Thus there is normally a pilotburner which, when alight, heats a first sensing element in the form ofa thermocouple and holds open a gas valve, failure of the pilot flamecausing closure of the gas valve and preventing the escape of gas.Secondly, there is a pressure governor which governs the pressure of thegas supplied to the main burner of the system during variations in thesupply pressure. The governor may consist of a loaded diaphragm which isconnected to a valve member, the diaphragm moving in response to sensedchanges in supply pressure and opening and closing the valve to maintainthe pressure of the gas supplied to the main burner substantiallyconstant.

Thirdly, there is normally a thermostat which, in the case of a domesticcentral heating system, may be responsive either to the fluid beingheated in the system or to the temperature of the ambient air or theremay be two thermostats each responsive to one of these quantities.

One known form of valve for use with a thermostat has a loaded diaphragmwhich has one side in a first chamber open to the gas supply pressureand the other side in a second chamber open to the gas supply pressurethrough a restriction. A weep pipe leads from the second chamber and thepassage of gas along this weep pipe is controlled by the thermostat. Ifthe weep pipe is closed then the pressure on both sides of the diaphragmis the same and the valve closes. If, however, the weep pipe is open,

3,374,952 Patented Mar. 26, 1968 ICC FIGURE 3 is a cross-section througha thermostat of the type used in the system of FIGURES 1 and 2;

FIGURE 4 is a cross-section through the control means used in the systemof FIGURE 1; and

FIGURE 5 is a view similar to FIGURE 4 of the control means used in thesystem of FIGURE 2.

Referring now to FIGURE 1, a gas supply is indicated at 10 and a maingas supply line at 11. The main gas supply line branches into a firstbranch 12 which is connected to main control means (13 which in turn isconnected by a line 14 to a main burner 15 of the system to becontrolled. The other branch 16 of the main gas supply line is connectedto auxiliary control means 17, the outlet of which is connected 'byaline 17a to a junction 18. From the junction 18 one line feeds a pilotburner 19. Another line 20a passes through a thermostat 20 to anauxiliary burner 21. A third line 22 is connected from the junction 18to the line 14.

As shown in the figure, the burners 19 and 21 are arranged adjacent toone another so that gas supplied to the auxiliary burner 21 will beignited by the pilot burner 19. Moreover, the pilot burner 19 isarranged to heat a thermal bulb 23 which is connected by a capillarytube 24 to the auxiliary control means 17. As will be describedhereinafter, the bulb'23 is filled with a liquid, preferably water,which vaporizes on being heated and displaces liquid along thecapilliary tube 24 to the auxiliary control means 17.

Similarly, the auxiliary burner 21 is arranged to heat a thermal bulb 25which is connected by a capillary tube 26 to the main control means 13.The bulb 25 is filled with liquid, preferably water, which vaporizeswhen heated by the auxiliary burner 21 and displaces liquid to a part ofthe control means 13 as will hereinafter be described.

The thermostat 20 controls the supply of gas to the auxiliary burner 21assuming that gas is being supplied to the junction 18.

Referring to FIGURE 3, the thermostat 20 comprises a housing 27 which isthreadedly engaged at 28 in the upper end of a container 29 containingthe liquid of, for example, a domestic central heating system. The body27 is provided with agas inlet 30 and a gas outlet 31 and these may becut off from one another by means of a valve member 32 having adepending flange 33 coming into contact with a peripheral valve seat,parts of which are indicated at 34. The valve'rnember- 32 is acted uponby a spring 35 and is urged to a downward position to cut off theinletfrom the outlet. The valve member also has secured thereto a rod 36which is threadedly engaged in a bore 37 in the valve member so that itmay be adjusted relative thereto, The rod 36 is received in a counterbore 38 in the upper end of a rod member 39. The lower the pressure inthe second chamber is less than that in the first chamber and the valveopens. The gas supplied to the weep pipe 'is usually fed to the mainburner after it has passed through the thermostat.

Two embodiments of the invetnion will now be described in detail by wayof example with reference to the accompanying drawings in which:

FIGURE 1 is a schematic diagram of a gas-burning system constituting oneembodiment of the invention;

FIGURE 2 is a schematic diagram of a gas-burning system constituting asecond embodiment of the invention;

end of the rod member 39 rests on the upper end of an Invar rod 40 whichis received in a brass tube 41 whose upper end is fixed in the housing27, the lower end 0 the Invar rod resting on the bottom of the brasstube.

Referring now to FIGURE 4, this shows in detail the 'main control means13 and its associated bulb 25. The

control means 113 comprises a housing having a first 'part 42- whichis'connected to a second part 43, the edge portion 44 of a diaphragm 45being trapped in a groove 46 between the parts 42 and 43. The part 42 isprovided with a gas inlet 47 and a gas outlet 48. The part is alsodivided by an internal wall '49 which is provided with a centralaperture 50,'the upper edge 51 of which provides a valve seat.

Secured to the diaphragm 45 and extending upwardly therefrom is a valvestem 52 which carries an inverted conical valve member 53 which as shownin FIGURE 4, can engage the valve seat 51 to shut off communicationbetween the gas inlet 47 and the gas outlet 48. The

3 upper end of the valve stem is guided in a valve guide 54 threadedlyreceived in an aperture 55 in the part 42.

The lower side of the diaphragm is connected to a spring 56 which actsas the diaphragm loading and the spring is contained in a cup 57 whichis threadedly engaged at 58 with the part 43 of the housing. A seal 59seals the joint between the cup 57 and the housing part 43. The cup 57is also provided with a knurled ring 60 whereby the cup can be rotatedrelative to the housing part 43 to vary the setting of the spring 56.

Secured to the housing part 43 is a first sheet metal casing member 61the interior of which is open to atmosphere through a small aperture61a, which at its lower end has an inturned flange 62 and which carriesa second casing member 63 having an out-turned flange 64 at its upperend which is engaged within the inturned flange 62. At its lower end,the casing member 63 has an inturned flange 65 which carries a block 66for a union nut 67 whereby the one end of the tube 26 can be connectedto the casing part 63. Mounted in the'casing member 63 is a bellows 69made of sheet metal and of known type, the mouth 70 of the bellows beingout-turned and being secured to the flange 64 of the casing member 63.The bellows is shown in FIGURE 4 in its fully extended position (itsfirst state) and is closed at its lower end by a plate 71 which isconnected by a nylon thread 72 to the underside. of a diaphragm 45, thenylon thread passing through an aperture 73 in the bottom of the cup 57.The casing part 63 comprises a chamber in which the bellows 69 aremounted.

The bulb comprises a tube 74 closed at its one end 75 and being brazedat its other end 76 to the other end of the capilliary tube 26. When thesystem is assembled it will be seen that the chamber 77 between thecasing member 63 and the bellows 69 is in communication with the tube 26which is in communication with the interior of the vessel 25. The vessel25 contains liquid, preferably water, so that when the vessel 25 isheated as will hereinafter be described, there will be a displacement ofwater into the chamber 77 which will result in a compression of thebellows 69. The nylon thread 72 is of such a length that, when thebellows is in its fully extended position as shown in FIGURE 4, thebellows bias the valve member 53 in contact with the valve seat 51 so asto cut off communication between the gas inlet 47 and the gas outlet 48.

The auxiliary control means 17 is identical to that shown in FIGURE 4except that it will be smaller in size. Moreover, the auxiliary controlmeans has a manual over-ride comprising a liquid-filled bellowsindicated at 78 in FIGURE 1 and connected by a capilliary tube 79 to thetube 24. Manual compression of the bellows 78 displaces liquid along thetubes 79 and 24 and compresses the bellows 69 in the auxiliary controlmeans 17 thus allowing the valve therein to open.

The operation of the system shown in FIGURE 1 will now be describedassuming that'all the flames are extinguished. It will first benecessary to light the pilot burner 19. The auxiliary control means 17will, if the system is cold, as has been assumed, cut off the supply tothe line 17a so it will be necessary manually to compress the bellows 78to allow the valve member 53 in the auxiliary control means 17 to liftthus to permit gas to flow into the line 17a. It will then be possibleto light the pilot burner 19. Similarly, assuming that the system iscold, the thermostat 20 will permit gas to flow from the line20a to theauxiliary burner 21 so that the gas issuing from this burner will beignited by the pilot burner.

The flame from the pilot burner 19 will then heat the bulb 23 with theresult that the water therein will vaporize and water will be displacedalong the tube 24 to the chamber 77 in the auxiliary control means 17.This will result in Compressing the bellows 69 (moving it to its secondstate) thus slackening the nylon thread 72 and allowing the valve member53 to rise and permit gas to flow from the inlet to the outlet and thusto permit a flow of gas through the control means both to the pilotburner 19 and, through the thermostat 20, to the auxiliary burner 21.When this has occurred, the bellows 78 can be released and the valvewill then operate under the action of the gas pressure. The diaphragm 45controls the valve member 53 in such a manner that it the gas pressurein the line downstream of the valve increases, the diaphragm will tendto be depressed against the action of the spring and will tend to bringthe valve member 53 closer towards the valve seat 51 thus reducing thesupply of gas. Conversely, if the gas pressure decreases the diaphragmwill tend to rise thus increasing the distance between the valve member53 and the valve seat 51. The diaphragm thus acts to maintain the gaspressure in the line 17a substantially constant.

When the pilot flame is initially lit, the main control means 13 will bein the position shown in FIGURE 4 thus the gas supply to the main burner15 will be cut off. When the auxiliary control means 17 is operatedinitially by the bellows 78, some gas will flow from the junction 18 andalong the lines 22 and 14 to the burner 15. This gas flow will only beat a low rate but the burner 15 will be ignited by the flame from thepilot burner 19. As the auxiliary burner 21 heats up the bulb 25, liquidwill be displaced into the chamber 77 in the main control means 13 thuscompressing the bellows 69 (i.e. moving it to its second state) andallowing the diaphragm 45 to act in the manner described in relation tothe auxiliary control means 17 and thus allowing a supply of gas to befed to the main burner 15. Assuming that the control is applied to adomestic central heating system, the burner 15 will then heat the liquidin the system. Some of this liquid will be supplied to the container 29of the thermostat. So long as the temperature of this liquid is below apredetermined value, the thermostat will allow gas to flow from theinlet 30 to the outlet 31 thereof and will thus maintain a supply of gasto the auxiliary burner 21. The thermostat is operated by virtue of thedifferent rates of thermal expansion of the Invar rod 40 and the brasstube 41. As the brass tube is heated, it will expand by a greater amountthan the Invar rod 40 so that the projection of the rod from the top ofthe tube becomes less. As a result, the rod member 39 moves downwardlyand allows the spring 35' to push the valve member 32 so that itsperipheral flange 33 seats against the seating 34 thus cutting offcommunication between the inlet and the outlet. It follows, therefore,that when the desired temperature is attained in the liquid, thethermostat will operate to cut off the supply of gas to the auxiliaryburner. The auxiliary burner will thus be extinguished and the vapor inthe bulb 25 will liquefy so that liquid will be displaced from thechamber 77 in the main control member 13 and this will assume theposition shown in FIGURE 4 thus cutting off the supply of gas from theline 12 to the main burner 15. However, there will be a small supply ofgas from the junction 18 along the line 22 to the main burner 15. Thiswill ensure that the main burner 15 will not be entirely extinguishedand the line 22 acts, as it were, as a by-pass to the main burner 15.The purpose of the by-pass is to avoid the noise of the main burnerlighting up when the main control means 13 opens.

When the temperature of the liquid in the system falls below thepredetermined value set on the thermostat, the brass tube 41 willcontract and will thus cause the Invar rod 40 to extend further from thetube 41 and will thus lift the valve member 32 to the position shown inFIG- URE 3 thus allowing'gas to flow to the auxiliary burner 21 and thisgas is ignited by the pilot burner 19. The flame from the auxiliaryburner 21 heats the bulb 25 and thus brings into operation once more themain control of flame failure, all the gas supplies are cut off. It willbe seen that if the auxiliary burner 21 is extinguished the main gassupply to the main burner will be cut off by the main control means 13.If the pilot burner 19 is extinguished then the vapor in the bulb 23will liquefy and the auxiliary control means 17 will move to theposition shown in FIGURE 4 and will thus cut off the gas supply alongthe line 17a. If the thermostat 20 is closed at this time, the auxiliaryburner will already have been extinguished and the main control means 13will be closed so that the main burner will be extinguished since no gascan now flow along the line 22. If the thermostat at 20 is open when thepilot flame fails, the main burner will be alight since the main controlmeans 13 will be open and gas will flow along the line 22 and throughthe thermostat 20 to the auxiliary burner 21. The main burner will thusbe kept alight until the thermostat 20 closes whereupon the auxiliaryburner 21 will be extinguished thus causing the main control means 13 toclose and extinguishing the main burner 13 since the auxiliary controlmeans 17 has already closed and no gas can thus flow along the bypass 22to the main burner. In order to start the system again, it will benecessary to operate the auxiliary control means 17 manually by thebellows 78 and light the pilot burner as described above.

Referring again to FIGURE 1, a second thermostat may be inserted in theline 20a in series with a thermostat 20. In a domestic central heatingsystem, there may be two thermostats, one being a thermostat 20 to sensethe temperature of the liquid in the system and the other thermostat tosense the temperature of the air in the space being heated. Thesethermostats are arranged in series so that if either is operated the gassupply to the auxiliary burner 21 is cut off with the result that onlythe reduced supply of gas is fed to the burner 15 through the by-pass22.

Referring now to FIGURES 2 and 5, these illustrate a somewhat simplifiedsystem in which there is only a single control means. Referring toFIGURE 2, there is a main gas supply 82 which feeds along the line 83 tothe control means 84. From the control means 84 a line '85 supplies gasto the main burner 86. From the line 83 there is a tapping 87 whichdivides into a line 88 which feeds a pilot burner 89 and a line 90 whichpasses through a thermostat 91, and if desired a second thermostat (notshown) to an auxiliary burner 93. The pilot burner 89 heats a bulb 94and the auxiliary burner 93 heats a bulb 95. The bulbs 94 and 95 areconnected by capilliary tubes 96 and 97 to each other and to the maincontrol means 84.

The main control means 84 is indicated in section in FIGURE 5 and it isbasically similar to the control means shown in FIGURE 4 so that similarparts are indicated by the same reference numerals in both figures. Thedifference between the two controls is that the nylon thread 72 in thecontrol of FIGURE 4 is replaced in that of FIGURE 5 by a nylon thread 98which is secured to the underside of the diaphragm 45 and has its otherend secured to one end of a tension spring 99. The other end of thespring 99 is secured to the plate 71 at the bottom of the bellows 69.When the system is cold the valve member 53 of the control 84 is held inits closed position by means of the tension in the spring 99. If onlyone of the bulbs 94 and 95 is heated by its appropriate burner then thiswill only displace suflicient liquid into the chamber 77 of the control84 to move the bellows 69 to relieve the tension in the spring 99. Thevalve member 53 will still be held closed by the thread 98. If both 6bulbs 94, are heated, however, there will be sufiicient liquid displacedinto the chamber 77 to cause the thread 98 to become slack and thus toenable the diaphragm 45 to act as a pressure governor'as described indetail in relation to FIGURE 4.

Operation of the system of FIGURE 2 is therefore similar to that ofFIGURE 1. The system is set into operation by first lighting the pilotburner 89. Assuming that the system is cold, gas will be suppliedthrough the thermostat 91 to the auxiliary burner 93 and this will alsolight. Both bulbs 94 and 95 will thus be heated and will release thediaphragm in the control means 84 so that gas is supplied to the mainburner 86. As the liquid in the system heats up, the thermostat 91 willbe operated to cut otf the gas supply to the auxiliary burner 93 whichwill thus be extinguished and the bulb 95 Will cool with the result thatthe valve in the control means 84 will close thus cutting off the supplyto the main burner 86. When the temperature of the liquid falls, thethermostat 91 will open thus supplying gas to the auxiliary burner 93which in turn heats up the bulb 95 and frees the valve in the controlmember 84 to supply gas to the main burner 15, the gas being lit by thepilot burner 89. Should the pilot burner 89 fail then the control 84will cut off the gas supply to the main burner even if the auxiliaryburner 93 remains alight. It is to be noted that in the system of FIGURE2, there is no by-pass supply to the main burner 86 as there is inFIGURE 1.

If desired the bulb 94 heated by the pilot burner may be omitted in thesystem shown in FIGURE 2 in which case the main control means 84 may beas shown in FIGURE 4 and controlled solely by displacement from the bulb95. The provision of both bulbs 94 and 95 does have the added safetyfeature that gas is not supplied to the main burner if either the pilotor the auxiliary burner is extinguished.

If desired, in any of the control means described the bellows may bemounted above the diaphragm 45 and may operate it through a push rod.

It will be seen that the invention provides a simple and versatile gascontrol system which is simpler than those heretofore provided.

What I claim then is:

1. A gas-burning system including a gas supply; a main burner; a mainburner, gas-supply valve interposed between and connected to the gassupply and the main burner and including a valve seat, a valve membercooperable with the valve seat to control the supply of gas to the mainburner and movable between open and closed positions, a diaphragmcommunicating on one side with the main burner and on its other sidewith atmosphere, means connecting the diaphragm with the valve member sothat the pressure of gas supplied to the main burner urges the valvemember to a closed position, spring means acting on the diaphragm tourge the valve member towards an open position, the diaphragm, springmeans and valve member acting as a pressure governor to control thepressureof gas supplied to the main burner; a chamber; a bellows ofvariable size mounted in the chamber and connected to the valve memberso that when the bellows is in a first state it holds the valve memberin its closed position against the action of said spring means and saiddiaphragm and when the bellows is in a second state it allows the valvemember to assume its open position and to move under the influence ofsaid spring means and said diaphragm; a pilot burner connected to thegas supply for igniting gas supplied to the main burner; an auxiliaryburner connected to the gas supply and disposed so as to be ignited bythe pilot burner; thermostaticallyoperated valve means interposedbetween the gas supply and the auxiliary burner to control the supply ofgas to the latter; a thermal bulb disposed so as to be heated by theauxiliary burner when the latter is alight; a conduit connecting thethermal bulb with said chamber and a vaporizable liquid in the thermalbulb, conduit and chamber such that when the auxiliary burner is alightthe liquid in the thermal bulb is vaporised thus displacing liquid alongthe conduit to the chamber to move the bellows to its second state andsuch that when the auxiliary burner is extinguished the liquid is notvaporised and the bellows is in its first state.

2. A system according to claim 1 including auxiliary control meansinterposed between the gas supply and the pilot burner to cut ofl? thesupply of gas to the pilot burner when the pilot burner, auxiliaryburner and main burner are extinguished.

3. A system according to claim 2 including a by-pass interposed betweenthe auxiliary control means and the main burner to supply the gas at alow rate to the main burner when the main burner, gas-supply valve isclosed.

4. A system according to claim 2 wherein the thermo statically operatedvalve means is interposed between the auxiliary control means and theauxiliary burner.

5. A system according to claim 2 wherein the auxiliary control meanscomprises an auxiliary gas supply valve including a valve seat, a valvemember cooperable with the valve seat and movable between open andclosed positions, a diaphragm communicating on one side with saidauxiliary burner and on its other side with atmosphere, means connectingthe diaphragm with the valve member so that the pressure of the gassupplied to the auxiliary burner urges the valve member to a closedposition, spring means acting on the diaphragm to urge the valve membertowards an open position, the diaphragm, spring means and valve memberacting as a pressure governor to control the pressure of gas supplied tothe auxiliary burner; an auxiliary chamber; a bellows of variable sizemounted in the auxiliary chamber and connected to the valve member ofthe auxiliary gas Supply valve so that when the bellows is in a firststate it holds said valve member in its closed position against theaction of said spring means and said diaphragm and when the bellows isin a second state it allows said valve member to move under theinfluence of the spring means and said diaphragm; a second thermal bulbdisposed so as to be heated by the pilot burner when the latter isalight; a second conduit connecting said second thermal bulb with saidsecond chamber and a vaporisable liquid in the thermal bulb, conduit andchamber such that when the pilot burner is alight the liquid in thesecond thermal bulb is vaporised thus displacing liquid along theconduit to the second chamber to move the bellows therein to its secondstate and such that when the pilot burner is extinguished the liquid isnot vaporised and the bellows in the second chamber is in its firststate.

6. A system according to claim 1 including a second thermal bulbdisposed so as to be heated by said pilot burner when the latter isalight, a second conduit connecting the second thermal bulb to saidchamber and a spring forming part of said connecting means between thevalve member and the diaphragm such that the liquid displaced from thethermal bulbs to said chamber with only one of the auxiliary and pilotburners alight is only sufficient to reduce the stress which occurs insaid spring when both of said burners are extinguished, the liquiddisplaced to said chamber When both the auxiliary and pilot burners arealight moving the bellows to its second state.

References Cited UNITED STATES PATENTS 1,875,388 9/1932 Magner 1581432,076,045 4/1937 Schaefer l58--l43 2,214,272 9/1940 Dillrnan 236682,265,294 12/1941 Lange 23668 2,286,296 6/1942 McGrith 236-68 2,384,6969/1945 Ray 158143 MYER PERLIN, Primary Examiner.

